1. Field of the Invention
The present invention falls within the field of transporting and conveying products, in particular bakery products, pastries and similar products.
Such a device will be particularly, but not exclusively, applicable to the transport of products in the form of dough rolls through different lines for them to be treated, in particular for baking.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 037 CFR 1.98
Preferably, the conveying of dough rolls is done within baking ovens, in particular continuous baking ovens.
In a known manner, such ovens include a baking enclosure provided with an inlet opening and an outlet opening, crossed through by a transport device, making it possible to convey baking supports such as plates, nets or similar members on which the products to be baked rest.
More specifically, the invention targets a transport device of the noria type providing upward and downward travel of the products within the baking enclosure. Such a noria includes at least one drive chain having links, preferably a pair of chains. Each one is wound at least around two deflection wheels, to describe a loop circuit. Such a circuit then includes at least an ascending chain strand and a second, descending chain strand, both of which are vertical.
Furthermore, support arms, which extend perpendicular and on which the trays of products to be baked rest, are securely fastened on each chain. The oven then includes a column of ascending plates and a column of descending plates.
It will be noted that at the upper end of the noria, a tray supported by a pair of arms located on an ascending column is transferred to a pair of arms of the descending column, using appropriate transfer means. At the lower end, the plates travel on an appropriate horizontal conveyor and are thus withdrawn upstream by the rising column and deposited at the downstream end by the descending column.
One example of such a transport device of the noria type is described in document EP 0,710,441.
Such a design of a transport device of the noria type, on which support arms are fixed perpendicularly, causes many mechanical constraints essentially due to the weight applied on the arms by the trays loaded with products, said weight being outwardly offset relative to the vertical median axis passing through the axis of said deflection wheels. This cantilever tends to cause the arms to sag downward at the ascending and descending strands of the chain. More specifically, this offset weight pushes each link back inwardly at its lower axis and outwardly at its upper axis, deforming the vertical linearity of the chain. To offset this deformation, it is then necessary to increase the tension applied by the deflection wheels considerably and check it regularly. This higher tension causes greater driving and motor means and also causes faster wear of the different parts, whether the links of the chain or the deflection wheels.
Furthermore, it is necessary to lubricate the various parts constantly, which increases the maintenance cost of such a device.
Furthermore, aside from keeping the arms in a perpendicular direction, perfectly horizontally aligned on either side at the ascending and descending strands, it is necessary to ensure that the arms remain in the vertical plane of their respective chain. To prevent this twisting of the chains, the current devices are equipped with guide means, often doubled, in the form of centering wheels. Although such guide means prevent the chain from twisting, they create friction, increasing the wear of the links and once again requiring increasing the tension applied on the chain.
Other guide elements are added, to ensure the vertical linearity of each strand. These elements assume the form of rails or rollers that cause the same drawbacks and once again require regular lubrication.
Document GB 2,129,451 describes an example device of the noria type, comprising a mount attached on each link and bearing on the mount situated just below it. However, the mount is positioned in front of each link and the bearing is done at the front of the chain, causing mechanical cantilever stresses.
Document U.S. Pat. No. 5,255,733 describes a particular chain, whereof half of the links have a specific shape. However, such a chain does not provide any support for the links relative to one another.
Document U.S. Pat. No. 3,317,029 targets a chain provided with mounts positioned laterally, but with an S shape, the bend of which is slanted on the upper rim of the mount situated below. This solution has a junction axis of two links, which blocks the mounts, without providing support because the mounts do not rest on one another.